South Korean Defense Minister Kim Kwan-jin Monday called on South Korean soldiers to prepare for North Korea provoking in other areas than the disputed sea border in the Yellow Sea.

"North Korea may provoke in a way which we cannot expect, although they are currently focusing on waters (in the Yellow Sea)," Kim told soldiers at a naval command in Pyeongtaek, Gyeonggi Province.

Kim was referring to recent violations of South Korean waters near the sea border with North Korea in the Yellow Sea by North Korean patrol boats and fishing vessels.

North Korea in recent years has challenged the Northern Limit Line (NLL), the de facto maritime sea border between the two Koreas drawn at the end of the three-year Korean War in 1953 unilaterally by the U.N. command, which dominated the sea and air border at the time.

"I understand that North Korea is trying to put our attention to the NLL with an aim to make the NLL as an object of negotiation," Kim said. "We actually did not imagine North Korea would provoke with (the torpedoing of) the Cheonan. I mean they can provoke by looking one way and going another."

Kim expressed concerns that North Korea may create domestic instability in South Korea, apparently noting political instability in North Korea after the ascendance to power by Kim Jong-un, a son of late North Korean leader Kim Jong-il.

The 28-year-old North Korean leader is believed to have consolidated power since taking over in December, but some analysts say it still remains to be seen. (Yonhap News)